So far, solar cells, in which a photoelectric conversion device comprising an inorganic material such as silicon is used, have been put to practical use. When producing a photoelectric conversion device comprising polycrystalline silicon, high-purity silicon is essential, but its cost is relatively high.
On the other hand, in general, a photoelectric conversion device comprising an organic material can be more easily produced compared to the photoelectric conversion device comprising the inorganic material. Therefore, its production cost can be reduced. Examples of solar cells comprising the photoelectric conversion device comprising the organic material include dye-sensitized solar cells, and solar cells comprising an organic semiconductor material called “organic thin-film solar cell”.
However, since electrolyte used in a typical dye-sensitized solar cell is usually a liquid (electrolytic solution), there may be a problem of such electrolytic solution leaking out or volatilizing from a space between a working electrode and an opposite electrode, etc. Thus, there is a problem that the photoelectric conversion device comprising the organic material has less durability compared to the photoelectric conversion device comprising the inorganic material.
Further, examples of the photoelectric conversion device comprising the organic material include: a photoelectric conversion device in which copper phthalocyanine as an electron donor is combined with a perylene derivative as an electron acceptor (C. W Tang, “Two-Layer organic photovoltaic cell”, Applied Physics Letters, 1986, Vol. 48 (Non-patent Document 1)); and a photoelectric conversion device in which polyphenylene vinylene as an electron donor is combined with a fullerene derivative (G Yu et al., “Polymer Photovoltaic Cells: Enhanced Efficiencies via a Network of Internal Donor-Acceptor Heterojunctions”, Science, 1995, Vol. 270 (Non-patent Document 2); Japanese National-phase PCT Laid-Open Patent Publication No. 8-500701 (Patent Document 1)).
However, the conversion efficiency of these photoelectric conversion devices is still low. For practical use, the conversion efficiency is desired to be further improved.    [Patent Document 1] Japanese National-phase PCT Laid-Open Patent Publication No. 8-500701    [Non-patent Document 1] C. W. Tang, “Two-Layer organic photovoltaic cell”, Applied Physics Letters, 1986, Vol. 48    [Non-patent Document 2] G Yu et al., “Polymer Photovoltaic Cells: Enhanced Efficiencies via a Network of Internal Donor-Acceptor Heterojunctions”, Science, 1995, Vol. 270